Add AOT and native image support

[OlgaMaciaszek]

Fixes gh-742.

[codecov]

Codecov Report

Merging #794 (fd1c364) into main (62f9d76) will decrease coverage by 4.03%.
The diff coverage is 35.04%.

Additional details and impacted files

@@             Coverage Diff              @@
##               main     #794      +/-   ##
============================================
- Coverage     78.54%   74.51%   -4.04%     
- Complexity      552      569      +17     
============================================
  Files            65       67       +2     
  Lines          2009     2201     +192     
  Branches        283      297      +14     
============================================
+ Hits           1578     1640      +62     
- Misses          268      394     +126     
- Partials        163      167       +4     

Impacted Files	Coverage Δ
...ringframework/cloud/openfeign/DefaultTargeter.java	100.00% <ø> (ø)
...k/cloud/openfeign/FeignCircuitBreakerTargeter.java	72.41% <ø> (ø)
...ud/openfeign/aot/FeignChildContextInitializer.java	8.51% <8.51%> (ø)
...gnClientBeanFactoryInitializationAotProcessor.java	11.84% <11.84%> (ø)
...work/cloud/openfeign/FeignClientSpecification.java	29.62% <21.42%> (+1.05%)	⬆️
...mework/cloud/openfeign/FeignAutoConfiguration.java	83.56% <33.33%> (-7.21%)	⬇️
...gframework/cloud/openfeign/FeignClientFactory.java	64.28% <37.50%> (ø)
...mework/cloud/openfeign/FeignClientFactoryBean.java	74.82% <87.50%> (+0.99%)	⬆️
...amework/cloud/openfeign/FeignClientsRegistrar.java	78.22% <88.63%> (+1.41%)	⬆️
... and 1 more